B cells-Why one specificity

Mike
A couple of things. I thought I read somewhere that TCR genes are alleleic
excluded. form your comment I guess its the beta chain (which makes sense).
whats interesting to me is the mechanics of allelic exclusion. the
methylation has got to be specific, granted, but are rearragnments taking
place on both chromosomes at the same time? And how did this process evolve
did it piggy-back itself on the process of imprinting. another topic was
touched on by someone else that made alot of sense and that is that a B cell
making 2 abs would have to have discrete assembly mechanics so that the
chains associated with their proper partner.
Have a happy and a merry! Mark H